list_units

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the burden of behavioral disclosure. The description states it lists all supported unit aliases, which is a read-only operation, but it does not mention any potential side effects, performance implications, or whether the list is static or dynamic. Given the simplicity of the tool, this is adequate but not rich.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, concise sentence that directly states the tool's function. It is front-loaded with the verb and resource, and there is no wasted wording. It is appropriately sized for a tool with no parameters.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's simplicity (no parameters, no output schema, no annotations), the description is complete enough. It clearly states what the tool does and its relationship to convert_units. However, it could mention whether the list is exhaustive or if there are any limitations, but for a listing tool, this is sufficient.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, and the schema coverage is 100% (since there are no parameters). The description adds value by explaining what the tool returns (a list of unit aliases) and its purpose (for convert_units). With no parameters, the description's role is to clarify the output, which it does effectively.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'List every supported unit alias for convert_units.' It specifies the verb (list), the resource (unit aliases), and the scope (every supported alias), which distinguishes it from sibling tools like convert_units. However, it doesn't explicitly mention the output format or how the list is organized, which could be slightly ambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage: it is meant to be used to discover unit aliases for convert_units. However, it does not explicitly state when to use this tool versus alternatives, nor does it provide any exclusions or prerequisites. The context is clear but not fully elaborated.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.